Kinetic Study of Methoxycarbonylation of Methylene Dianiline with Dimethyl Carbonate Using Lead Acetate Catalyst

Methylene diphenyl dicarbamate (MDC) is a. key intermediate in the non phosgene manufacture of methylene diphenyl diisocyanate. The synthesis of MDC by methoxycarbonylation of methylene dianiline (MDA) with dimethyl carbonate in the presence of lead acetate catalyst, which showed high catalytic activity, was studied. Complete conversion of MDA and 98.10% yield of MDC were achieved under optimum conditions. To quantify the influence of both the temperature and reaction time, the kinetic parameters were investigated in the presence of Pb(OAc)(2)center dot 3H(2)O. A consecutive reaction model was established by simplifying the methoxycarbonylation process, and the two steps were confirmed to be first-order reactions by the integral test method and the numerical differential method, respectively. The results showed that the activation energies of the two steps are 175.84 and 177.92 kJ/mol, with the frequency factors being 1.91 x 10(20) and 1.98 x 10(20), respectively. Based on the kinetic model obtained, the progress of the reaction can be calculated under given conditions.